Shadows are a default setting and in some cases need to be turned off. If the colours do not appear to be right, play around with the Shadow tool. Find the Shadow tool under the ‘Visualize’ tab in the ’Advanced’ settings on the top left corner of the page. You can also set the shadow to any given settings depending on dark or light you want the shadow effect.
You can also watch this short video to show you exactly what the tool can do: